Adipocyte plasma membrane-associated protein (APMAP)
The protein contains 416 amino acids for an estimated molecular weight of 46480 Da.
Exhibits strong arylesterase activity with beta-naphthyl acetate and phenyl acetate. May play a role in adipocyte differentiation. (updated: March 4, 2015)
Protein identification was indicated in the following studies:
- Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
- Lange and co-workers. (2014) Annotating N termini for the human proteome project: N termini and Nα-acetylation status differentiate stable cleaved protein species from degradation remnants in the human erythrocyte proteome. J Proteome Res. 13(4), 2028-2044.
- Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
- Wilson and co-workers. (2016) Comparison of the Proteome of Adult and Cord Erythroid Cells, and Changes in the Proteome Following Reticulocyte Maturation. Mol Cell Proteomics. 15(6), 1938-1946.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
This protein is predicted to be membranous by TOPCONS.
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| Variant | Description |
|---|---|
| dbSNP:rs12242 | |
| dbSNP:rs35097515 | |
| dbSNP:rs28364786 |
Cellular Component
Cell surface
Endoplasmic reticulum
Extracellular exosome
Integral component of membrane
Membrane
The reference OMIM entry for this protein is 615884
Adipocyte plasma membrane-associated protein; apmap
Chromosome 20 open reading frame 3; c20orf3
Bscv
DESCRIPTION
APMAP shares similarity with the paraoxonase family of enzymes (see PON1, 168820) and may catalyze antioxidative detoxification reactions (Ilhan et al., 2008).CLONING
By computational analysis, Morita et al. (2000) identified APMAP, which they called BSCV. The deduced BSCV protein contains 416 amino acids and shares 25.8% identity with Arabidopsis strictosidine synthase. Albrektsen et al. (2001) cloned mouse Apmap, which shares 89% nucleotide identity with human APMAP. The deduced 415-amino acid mouse protein has a calculated molecular mass of 46.5 kD. It has a short N-terminal domain, followed by a transmembrane domain and a long C-terminal domain. Northern blot analysis of adult mouse tissues detected a 2.2-kb Apmap transcript that was highly expressed in liver, heart, and kidney, with lower expression in brain and lung, and very low expression in spleen, skeletal muscle, and testis. Quantitative PCR detected 4.3-fold higher Apmap expression in mouse adipose tissue than in liver. In vitro translation, cell fractionation, protein extraction, and biotinylation experiments revealed that Apmap was expressed as a glycosylated integral plasma membrane protein with a large extracellular C-terminal domain and a short cytoplasmic N-terminal domain. Ilhan et al. (2008) determined that full-length human APMAP, which they called C20ORF3, is likely to fold into a 6-bladed beta-propeller structure similar to PON1 and plant strictosidine synthase. Within its C-terminal domain, APMAP contains 2 potential glycosylation sites and 3 cysteines, at least 2 of which are predicted to be involved in intra- or intermolecular disulfide bond formation. EST database analysis revealed an APMAP splice variant lacking exons 3, 4, and 5, which was predicted to encode a truncated protein containing the cytosolic domain. Northern blot analysis detected variable expression of a major 2.4-kb APMAP transcript in all adult and embryonic human tissues examined, with highest expression in adult liver, placenta, and heart and in embryonic liver and kidney. Western blot analysis detected a predominant 50-kD protein in liver and placenta. A glycosylated 52-kD band and a 32-kb C-terminally truncated isoform were also observed. Immunofluorescence and immunohistochemical analyses of kidney detected strong APMAP staining in glomerulus and tubule epithelial cells and in vascular endothelial and smooth muscle cells. Strong staining was also detected in hepatocytes and pancreatic islets of Langerhans. FACS analysis showed APMAP expression on monocytes, but not on granulocytes or lymphocytes. In fractionated Rin-F5 rat pancreatic beta cells, the 50-kD Apmap isoform was detected in the heavy membrane fraction, whereas the 32-kb form was detected in the cytosol.GENE FUNCTION
Albrektsen et al. (2001) found that Apmap was not expressed in mouse 3T3 or primary rat preadipocytes, but was induced following their differentiation into adipocytes. By assaying membrane fractions of transfected Rin-F5 and HepG2 cells, Ilhan et al. (2008) found that human APMAP showed arylesterase activity against beta-naphthyl acetate and phenyl acetate. Calcium chelation reduced, but did not eliminate, the arylesterase activity. Serum deprivation reduced surface expression of APMAP in HEK293 cells, and serum stimulation increased both APMAP reporter gene activity and cell surface APMAP expression.GENE STRUCTURE
Ilhan et al. (2008) determined that the APM ... More on the omim web site
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 615884 was added.